1. Field of the Invention
The present invention relates generally to a solid state imager and more particularly to a solid state imager of an amplifying type having an amplifying element at every photo receptor portion.
2. Description of the Prior Art
In a typical conventional solid state imager using a charge coupled device (CCD), a signal charge whose amount depends on incident light quantities stored in a photoelectric converting portion of each pixel is directly transferred to an output portion by means of the CCD, so that there has been such a drawback that the signal-to-noise (S/N) ratio of the signal change is likely to be degraded since noise components are contaminated into the signal charge during the transferring thereof by the CCD.
In order to obviate this drawback of the conventional solid state imager, there has been proposed a solid state imager of an amplifying type wherein there are provided a photo receptor portion having a photoelectric converting portion for storing a signal charge whose amount depends on incident light quantities, a unit for amplifying the signal charge accumulated in the photoelectric converting portion, and a unit for resetting an input of the amplifying unit is provided for each of a plurality of pixels arranged in a matrix or two-dimensional configuration, as disclosed in, for example, Japanese Patent Laid-Open Publication No. 1-154678.
However, in this conventional amplifying type solid state imager, the fixed pattern noise due to defects of elements can be reduced by improving the manufacturing process of the imager, but the reset noise due to the characteristics etc. of the elements is hardly reduced since it is originated from the principle of the elements. Further, the conventional amplifying type solid state imager is of the front-illumimated structure, and so the numerical aperture is disadvantageously small.